This invention relates to a method and system for direct and diagnostic prospecting of hydrocarbon deposits.
The use of electrical geophysical techniques in the search for subsurface anomalies is well known in applications such as the search for metallic ores, sulphides, groundwater, and hydrocarbons. These systems rely on the measurement of the electrical response in the earth to either natural magnetotelluric currents or currents induced from a man-made source.
In electrical prospecting for hydrocarbons, the effects of hydrocarbons on the electrical characteristics of rocks are generally very difficult to separate from other electrical effects due to geological structure, near surface inhomogeneities, and magnetotelluric noise. Prior art electrical hydrocarbon prospecting methods use interpretation techniques which rely on mathematical modelling in an attempt to determine the thickness and resistivity of the various layers in the earth, which is an indirect approach.
The interpretation techniques used in these prior art methods are extremely time-consuming and are incapable of processing the large amount of field data required to reliably and diagnostically determine the presence of hydrocarbons. They are limited to being able to delineate a very small number of resistive layers.
It would be very helpful in the search for hydrocarbon deposits using electrical geophysical methods if a much larger quantity of data was collected and interpreted in order to more diagnostically distinguish the electrical responses due to hydrocarbons from the responses due to other electrical anomalies.
Because of the limitations on the quantity of data that may be interpreted in prior art methods, the transmitting and receiving equipment and field arrays used in these prior art methods to produce and measure the effects of induced currents in the earth have not been designed or built to accommodate the combination of a large number of transmitting array configurations, frequencies, and receiving array configurations. Thus, these prior art techniques have had severe limitations in direct and diagnostic prospecting for hydrocarbons.